People Adapted to the Cold and Got More Migraines as a Result

(NEW SCIENTIST) – 3 MAY 2018 – By Jessica Hamzelou –Some people have adapted to live in cold polar climates, but at a price. The same gene variant that helps us cope with cold also seems to increase our risk of migraine.

Aida Andrés at University College London, UK, Felix Key at the Max Planck Institute for Evolutionary Anthropology in Leipzig and their colleagues studied the gene for a protein called TRPM8, which is known to activate in cold temperatures.

The gene for the protein comes in two flavours. An older variant, which we share with chimpanzees, is common in people living in Africa. But a newer variant is more common in people living in northern countries, particularly in Europe.

The team screened databases of genetic data taken from people across the world, to see how common each gene variant was in Europe, Africa and South East Asia.

“We found a correlation between frequency [of the gene] and latitude,” says Key. For example, the new variant of the gene is found in around 88 per cent of Finnish people, but only 5 per cent of Nigerians.

“It’s really cool,” says Mark Shriver at Penn State University in University Park. “This is probably the first time [the adaptation of] a sensory gene has been tied to environment.”

A right old headache

The TRPM8 gene has also been linked to migraine. The older variant is thought to protect against the disorder, while the newer variant increases the risk. This may help explain why migraine is more commonly reported in northern countries. “We know the prevalence of migraine is lower in African Americans,” says Key.

It’s not clear why sensations of cold might be linked to migraine, although some people do experience cold-triggered headaches. “That ice cream headache you get is the first thing that comes to mind,” says Shriver.

But migraine is complex, and many factors affect a person’s risk of developing it, says Andrés. In a second study, Padhraig Gormley at Massachusetts General Hospital and his colleagues have shown that many common genetic variants shape a person’s risk of developing migraine (Neuron, DOI: 10.1016/j.neuron.2018.04.014).

It’s also not clear why the often-debilitating pain of migraine would be beneficial. The increased migraine risk associated with the gene variant is probably an unfortunate side effect, says Shriver.

The finding is more evidence that humans have evolved and adapted over the last 100,000 years, even though today we are more alike genetically than most species, says Rasmus Nielsen at University of California, Berkeley.